The disclosure relates to apparatuses, systems and methods for monitoring the abdomen during pregnancy, and assessing fetal risk, particularly while sleeping.
Medical evidence suggests that large amounts of mass or pressure in the abdominal region can lead to serious health consequences. Two very closely related examples of this are intra-abdominal hypertension (“IAH”) and abdominal compartment syndrome (“ACS”). In these conditions, fluid within the abdominal space accumulates in such large volumes that the abdominal wall stretches to its elastic limit. Once it can no longer expand, additional fluid leaking into the tissue results in a rapid rises in the pressure within the closed space. Initially, this increase in pressure causes mild to moderate organ dysfunction (as seen in IAH). If the pressure continues to rise to higher levels, organs may begin to fail completely (as seen in ACS), which can lead to death.
A similar pathogenesis is observed in pregnant women, who also can have negative clinical responses to their large abdominal masses. The abdomen as a whole may apply different amounts of pressure on intra-abdominal tissues and organs depending upon its orientation. Compression of abdominal veins by the growing uterus explains many symptoms of preeclampsia. Inferior vena cava (“IVC”) compression has been shown to decreased flow in the uterine, portal, hepatic, splenic, and renal veins. This reduced flow directly or indirectly contributes to lower extremity edema, fetal-placental ischemia, a glomerulopathy with proteinuria, and hypertension. Placental-fetal ischemia can lead to expression of soluble fms-like tyrosine kinasel (“sFLT”) and endoglin which have been shown to cause additional diffuse endovascular damage. Increased renal venous pressure could lead to an increased release of renin with conversion of angiotensinogen to angiotensin and secretion of aldosterone, leading to sodium and water retention, and increased systolic and diastolic blood pressure. In addition, IVC flow restriction would be expected to decrease venous return from the lower extremities and lead to the peripheral edema commonly present in preeclamptic women.
Preeclampsia is significantly more common in women whose abdomen has not been previously stretched, in severely obese women, in women who have a large time gap between pregnancies, in multi-fetal pregnancies, and is twice as frequent in women with preexisting chronic hypertension. Further, preeclampsia almost never occurs prior to 20 weeks (when fetus starts to gain significant mass), and its risk increases incrementally every week until delivery at which point it precipitously drops to almost zero. Women with preeclampsia have a 40% increased incidence of delivering a baby with high birth weight for gestational age. Additionally, preeclampsia rates are significantly higher in women with hypolumbarlordosis, a purely mechanical abnormality of the spine that positions the uterus in more direct contact with the IVC.
Traditionally, obstetricians have advised pregnant women with preeclampsia or other hypertensive disorders to avoid lying in the supine position and to go on bed rest for periods of time; however, these recommendations are often incomplete as they only frame the issue in terms of “good positions” (e.g. bed rest, laying on left side) and “bad positions” (e.g. laying supine). As a result, there is a need in the art for a method of developing more tailored recommendations for pregnant women with preeclampsia or other hypertensive disorders.
Various prior art home-use wearable pregnancy devices monitor metrics such as fetal heart rate and uterine contractions. This data may improve resultant care in a small number of cases, they typically result in urgent reactionary medicine in the last month of gestation, and frequently generate false positive alerts. In contrast, the presently disclosed devices, systems and methods were developed on the premise that there are a large number of user physiologies and behaviors that have profound impacts on pregnancy outcomes that can be monitored and improved throughout pregnancy.
Many complications of pregnancy which cannot simply be fixed once they manifest. Despite decades of research into the etiology of preeclampsia, its exact pathogenesis remains uncertain; however, it is becoming increasingly apparent that preeclampsia is directly related to underlying placental pathology and dysfunction that develop over many months. Because preeclampsia is not a disease that can be fixed at the end of pregnancy, prevention is important. The various implementations of the system discussed herein relate to the acquisition of risk factor data relating to the user's physical position, such as when sleeping, snoring and the like.
As most cases of preeclampsia occur at the end of pregnancy, the best way to prevent the majority of cases is to delay onset of dangerously high blood pressure until the pregnancy is full-term. The presently disclosed system tracks the adjustable factors in pregnancy that can prevent diseases and negative conditions. By way of example, these adjustable factors include the following. Sleep disordered breathing leads to hypertension in both pregnant and non-pregnant individuals. Similarly, snoring and sleep apnea are highly correlated to hypertensive diseases of pregnancy such as preeclampsia, as well as gestational diabetes and premature birth. Uterine artery blood flow and fetal oxygenation are both shown to significantly decrease in the supine position. Numerous studies have now shown that women who spend significant time in reclined and supine positions have much higher rates of stillbirth and intrauterine growth restriction. Depression and stress double the risk of preterm birth even after covariants such as low economic status and drug use are excluded. This is not surprising as depression is known to cause hypertension and increase placental and fetal cortisol levels.
The placenta serves as the lungs, kidneys, liver, endocrine system, and immune defense of the fetus. Despite its enormous importance, the placenta is arguably the least understood of all human organs. This is partly because the development of the human placenta cannot be invasively studied because it only exists during pregnancy at which time it is performing life-maintaining duties for the fetus. Not surprisingly, as we learn more about this mysterious organ, we also learn of its great importance in protecting the fetus from potential hazards during the pregnancy.
There is a need in the art for improved fetal monitoring devices, systems and methods.